Detection of Gaseous Nuclei in Centrifugal Motor Pumps by Analysis of Their Estimated Torque

This article evaluates the ability of the load torque signature analysis (LTSA), which is a mechanical fault detection method, to detect gaseous nuclei in centrifugal pumps driven by induction motors supplied by frequency inverters. The LTSA method is described and some modifications are implemented in it to improve its performance when the motor operates under nonsinusoidal voltages such as those generated by frequency inverters. Initially, these improvements are checked by means of simulations. Then, LTSA is applied to a laboratory hydraulic plant in order to validate the method. Experimental results are plotted and compared to previous results obtained from the same system, but with the motor supplied directly from the mains.